This invention relates to a clip-like and self-locking sheet-metal nut. Sheet-metal nuts of this type are typically used to fasten or hold together, in combination with a sheet-metal screw, flat plates, such as, for example, flat pieces of sheet-metal. In this connection, the nuts are made so that they bear against the threaded core of the screw with a spring force that prevents the screw from working loose through shocks or vibrations, that may occur, for example, in a motor vehicle.
Such a sheet-metal nut is shown, for example in U.S. Pat. No. 3,308,708. This sheet-metal nut has a helical slot that is adapted to engage the helical thread of the screw and a pair of resilient fingers integral with the portion of the nut forming the helical slot that curve upwardly and inwardly and are bent over to such an extent that curved clamping edges at their free ends are at a smaller distance from one another than the core diameter of the screw to be screwed into the nut. When the screw is screwed in, the edges of the fingers are pushed apart, with the fingers springing up over the entire length as far as they engage with the threaded leg of the screw and pressing inwardly against the core of the screw to keep it in place.
These fingers, however, are relatively weak because they bend over their entire length and therefore do not always provide the required clamping force desired. It has also been shown that the clamping force tends to weaken after repeated slackening, so that these sheet-metal nuts can only be re-used to a limited extent.